Back support



FIG. 1 is a front view of the back support;

FIG. 2 is a sectional view of the back support, taken along line 2-2 inFIG. 1;

FIG. 3 is a front view of the back support; and,

FIG. 4 is a sectional view taken along line 4-4 in FIG. 3.

The bottom of the back support is flat and unornamented.

The ornamental design for a “back support,” as shown and described.